The present invention relates to the field of semiconductor devices. More specifically, the present invention relates to an apparatus and method for forming a packaged semiconductor device having stacked die.
Packaged semiconductor devices containing multiple semiconductor die provide high device density. In addition, packaged semiconductor devices containing multiple semiconductor die can provide increased functionality and performance.
Packaged semiconductor devices containing multiple semiconductor die typically include a first semiconductor die that is attached to a package substrate. Bonding pads are disposed around the periphery of the top surface of the first semiconductor die. Wire bonds electrically connect to the bonding pads on the first semiconductor die and electrically connect to corresponding bonding pads located on the package substrate. The spacer is then attached to the center of the top surface of the first semiconductor die.
The second semiconductor die is attached to the spacer. Bonding pads disposed on the top surface of the second semiconductor die are then electrically connected to bonding pads on the package substrate using wire bonds. Encapsulant is then applied so as to cover the semiconductor die and all of the wire bonds.
The manufacturing process for forming packaged semiconductor devices containing multiple semiconductor die is expensive. More particularly, spacers add cost to the manufacturing process. In addition, the spacer must be precisely placed so as to prevent damage to wire bonds.
Also, it is difficult to apply encapsulant such that the encapsulant will completely fill the areas surrounding the spacer. Often, air is trapped under the second semiconductor die in the areas surrounding the spacer. This causes voids within the encapsulant in the areas surrounding the spacer. This leads to a packaged semiconductor device having reduced structural integrity. Also, the voids can trap moisture, leading to reliability problems.
What is needed is a packaged semiconductor device and a method for forming a packaged semiconductor device having improved structural integrity and reliability. Also, a method and apparatus is needed that meets the above need while reducing manufacturing cost. The present invention meets the above needs.
The present invention provides a method for forming a packaged semiconductor device and a packaged semiconductor device in which encapsulant is used for separating stacked semiconductor die. The method and apparatus of the present invention reduces manufacturing cost while improving structural integrity and reliability.
A method for forming a packaged semiconductor device having stacked die and a packaged semiconductor device having stacked die are disclosed. A first semiconductor die is coupled to a ball grid array substrate. Wire bonds are then coupled to the first semiconductor die and to the ball grid array package substrate so as to electrically couple the first semiconductor die to the ball grid array package substrate.
Encapsulant is disposed over the first semiconductor die and over the wire bonds. The encapsulant is then at least partially cured. The encapsulant completely fills the area surrounding the first semiconductor die. Accordingly, no air pockets are formed that can cause integrity problems or reliability problems as can occur in prior art processes that use spacers.
A second semiconductor die is coupled to the encapsulant. In one embodiment, the second semiconductor die at least partially overlies the first semiconductor die. The second semiconductor die is then electrically coupled to the ball grid array substrate.
Encapsulant is then applied and cured to form a second layer of encapsulant that covers the second semiconductor die. The second layer of encapsulant completely fills the area surrounding the second semiconductor die. Accordingly, no air pockets are formed that can cause integrity problems or reliability problems as can occur in prior art processes that use spacers.
Because a spacer is not required, the method and apparatus of the present invention results in cost savings. Moreover, because the method and apparatus of the present invention does not result in the formation of voids, reliability and structural integrity problems are avoided as compared to prior art processes that use spacers.